In recent years, hybrid vehicles, which are allowed to run by a combination of the driving force of a motor and the driving force of an engine, have been developed, and put to increased practical use. Among the hybrid vehicles are, for example, those adopting the series method in which the vehicle is run by the driving force of the motor, and the engine is used as a power source for an electric generator, and those relying on the parallel method in which the vehicle is run by the driving forces of both of the engine and the motor (or the driving force of the engine alone). Alternatively, there are those which switch among the following travel modes according to the operating situation of the vehicle: an EV travel mode in which the vehicle is run by the driving force of the motor alone; a series travel mode in which the above series method is applied; and a parallel travel mode in which the above parallel method is applied.
In switching among these travel modes, a clutch provided in a power transmission mechanism is disengaged or engaged to switch among the paths of power transmission. That is, the motor is connected to driving wheels, and the engine is connected to the driving wheels via the clutch. In the EV travel mode and the series travel mode, the clutch remains disengaged, and only power from the motor is transmitted to the driving wheels. In the parallel travel mode, the clutch is in an engaged state, and the power of the engine and the power of the motor are transmitted to the driving wheels.
As a clutch control device for controlling the clutch in the above manner, the one described in Patent Document 1, for example, is known. The clutch control device described in Patent Document 1 is a clutch control device for controlling a clutch, the clutch comprising a pair of engaging members provided in a power transmission path of a vehicle and relatively moving in an axial direction to engage with or disengage from each other; and a driving means for exerting a driving force on at least one of the pair of engaging members to direct it toward the other engaging member, according to a command value inputted to the driving means, wherein the clutch control device exercises engagement control for inputting into the driving means a predetermined command value preset as a command value which brings the pair of engaging members into a completely engaged state and, if the pair of engaging members are not judged to be in the completely engaged state after the predetermined command value has been inputted to the driving means in the engagement control, the clutch control device changes the command value to a value corresponding to a greater driving force than a driving force corresponding to the predetermined command value. That is, with this clutch control device, when the engaging members of the clutch are judged not to have been engaged in the clutch engagement attempts even in the presence of a temporary inclination or snagging, control is exercised so as to increase the driving force exerted on the engaging members, thereby engaging the clutch.